Chronograph



Sept; 15, 1936.

H. A. MORRISS CHRONOGRAPH Filed Aug. 20, 1932 mill IIIIIIIII u: E

R O E m m M 0 ww m 1. r u. m w W H Patented Sept. 15, 1936 UNlTE STATES PATENT OFFIQE CHRONOGRAPH A. Morriss, deceased Application August 20, 1932, Serial No. 629,620

2 Claims.

This invention relates to a new and useful improvement in chronographs.

An object of the invention is to provide a simple and efiicient construction whereby when the l chronograph is actuated the hook-up between the drive mechanism and the recording needle will be instantaneous and accurate and entirely free from the slippage which heretofore has easily occurred.

A further object is to provide a mechanical means whereby upon starting of the chronograph to record seconds or split seconds the connection between the driving member and the driven member will be instantaneous and positive regardless of the position of the two members just prior to their connection.

A further object is to provide a mechanism which can be designed to effect a positive relation regardless of whether the chronograph is to record /5th of a second or other minute fractions of a second.

A still further object is to provide a mechanism which will simply and efiiciently insure that the recording needle will always be restored to zero 5 position and will always register with a seconds graduation accurately.

Further and more specific objects, features and advantages will more clearly appear from a con sideration of the specification hereinafter taken in connection with the accompanying drawing which forms part of the specification and which illustrates a present preferred form of the invention.

Briefly considered the invention concerns the provision of a driving gear having a predetermined series of ratchet teeth thereon which are adapted to be automatically related and connected to a clutch plate having a similar number of ratchet teeth thereon, provided with means whereby at least one of the teeth on the clutch plate is positively engaged with the teeth on the driving gear whenever a hook-up occurs regardless of their instantaneous relative position just prior to contact.

In other words the invention comprises means whereby the constantly driven member having ratchet teeth can be completely and positively hooked up at any instant of time however small with a member to be intermittently driven so that the connection between the two is complete and avoids slipping and inaccuracies which have heretofore been present in chronographs.

The invention more particularly concerns a driving train having a predetermined number of ratchet teeth thereon the number of said teeth.

bearing a predetermined relation to the number of seconds of said gear in one revolution com bined with a clutch plate having a relative number of ratchet teeth thereon adapted to be engaged at any instant with the teeth on the 5 drive gear. The distance between the teeth on the clutch plate is the distance between a given number of teeth on the driving gear plus a predetermined fraction of the distance between the adjacent teeth on the driving gear. This differ- 1o ential relation causes at least one tooth on the clutch plate to be definitely and positively hooked up with the teeth on the drive gear whenever the chronograph mechanism is started and to record small fractions of time such as split seconds.

For example in a drive gear having one hundred teeth and revolving in one hundred seconds, the space between the adjacent teeth represents one second. If the chronograph is to record onefifth of a second the clutch plate will be milled 20 with ninety-nine teeth, namely, one tooth less than the number on the drive gear. After this all the teeth on the clutch plate will be milled off with the exception of the 1st, 20th, 40th, 60th and th. The distance between the 1st and 25 20th it will be observed will be substantially equal to the distance between twenty teeth on the drive gear plus one-fifth of the distance between the adjacent teeth on the drive gear. The distance between the first tooth on the clutch plate and 30 the thirteenth tooth will be equal to the distance between the fortieth on the drive gear plus twofifths of the distance between the adjacent teeth on the drive gear. This relation continues proportionally around the clutch plate. In the man- 35 ner set forth in detail hereinafter the differential relation of the teeth on the drive gear and the clutch plate can be designed and arranged in accordance with the desired number of beats per second of the escapement to register in terms 40 of units of time as small as one thousandth of a second.

The preferred present form of the invention is shown in the drawing of which:

Fig. l is a section taken on the line of Fig. 45 2 looking in the direction of the arrows.

Fig. 2 is a partial plan view of the chronograph with the dial removed;

Fig. 3 is an elevation of the clutch wheel and heart-shaped cam assembly, with the cam shown 50 in section;

Fig. 4 is an inverted plan view of the clutch wheel;

Fig. 5 is a plan view of the seconds wheel;

Fig. 6 is an elevation of the seconds wheel; and 55 Fig. 7 is an inverted plan View of the block wheel.

Describing only the construction and leaving the operation of the device to be described hereinafter, it will be noted that the chronograph includes a frame plate l, a cook or projecting lug 2 and the lower supporting bar 2'. These elements represent the frame of the construction. The clutch wheel 3 supports a heart-shaped cam 3 and the arbor of the clutch wheel 3 is supported and journalled between the cock or lug 2 and the frame bar 2'. The train wheel 5 is rotatably mounted in any suitable. manner on the arbor of the clutch Wheel 3 and preferably this train wheel has the usual pinion 6. This train wheel 5 and the pinion 5 form part of the ordinary train that drives the escapement and is always running. This train wheel with its pinion turns freely and independently of the arbor of the clutch wheel 3. I

On the upper surface of the train wheel 5 are disposed a designated or desired number of contrite ratchet teeth .l preferably on the upper side facing the clutch wheel The clutch wheel at its lower face preferably facing the ratchet teeth 'I is provided with a plurality of clutch teeth 8, the function and operation of which will be hereinafter described. A washer 9 is disposed around the arbor of the train gear 5 and across the top of the pinion 6 and acts as a surface on which the end H of a lever it bears.

This lever it is pivoted at one end to the. plate 1 and at the other end bears against the top of the pinion Disposed on the top of plate I is the usual block wheel 52 fastened to the plate by a screw i3. This block wheel at its lower side is provided with a plurality of countersinks or depressions i i of which six are shown in the drawing. These countersinks are adapted to be engaged as the block wheel l2 rotates by an upwardly projecting pin or stud E5 on the lever it? which stud projects through an opening in the plate I.

Considering Fig. 2 it will be seen that the lever E8 pivoted on the plate i is acted upon by a spring so that its outer end is always pressed against the heart-shaped cam i. The lever and spring unit ll acts as a brake on the edge of the clutch Wheel 3 and is provided at its opposite end with a pawl adapted to be successively engaged by the blocks on the wheel E2 in the usual manner. The lever l9 also mounted on the plate i has a detent or projecting pin 26 which can be operated by hand so that the pawl can in the usual manner shift the block wheel l2 one tooth each time the pin 20 is actuated. A spring is disposed between the pinion 6 and the frame bar! 2' and tends to push'the pinion and the train gear 5 always upwardly into contact with the clutch wheel 3. A backing screw 23 is adjustable in the plate I so as to predetermine the upward limit of movement of the lever id. In Fig. 2 the hand or pointer 2! is intended to be shown in the zero position.

In the operation of the device the parts are 'shown in Fig. 2 as the position of engagement wherein the pointer is at zero and everything is at rest with the exception of the continuously moving pinion 6 and train gear 5 with the elements which directly engage with them such as the escapement and the spring drive. When the pin 20 is moved to the left of the position shown in Fig. 2 the pawl on the end of the lever M? will engage the tooth of the block E2 in the usual manner and move said wheel in a counter-clockwise direction a distance of one tooth. This movement will cause one of the blocks of the wheel 52 to engage a projection on the lever i6 and move the outer end of the lever away from the cam 4. At the same time one of the countersinks or depressions M on the bottom of the block wheel i2 is moved to a position permitting the pin i5 on the lever 58 to move upwardly thereinto thus permitting the. spring 22 to force the pinion 6 and the train gear 5 upwardly against the resistance of lever 55 to such a position that the contrite teeth i on the train gear engage with the ratchet teeth 8 on the clutch wheel. This engagement which will be described in detail hereinafter causes the two wheels 3 and 5 to move substantially as one carrying a recording hand or dial forward. When the'lever 26 is pressed the second time the block wheel 52 is again turned. This time the countersinks i i move away from the top of pin l5 thus depressing the lever iii and forcing the pinion S and the train gear 5 downwardly against the action of spring 22 out of contact with the clutch Wheel 3. At the same time the block of the wheel i2 which has been holding the brake element 8'? away from the clutch wheel by reason of the engagement of the pawl and the brake ill with one of the blocks on the wheel 52 is due to this second movement of the block wheel effective to allow the spring conn cted to the brake H to push the brake element i? against the edge of the clutch wheel to stop the same instantly. Thus the block of the wheel 52 previously engaging the pawl on the brake unit is moved out of engagement or out of the path thereof permitting the pointer to drop into the space between the blocks. This will hold the indicator hand 2! firmly at the point of recording.

The third movement of the pin 28 lifts the brake H by reason of the engagement of the next block of wheel l2 with the pawl of the brake unit. At the same time the other block of the wheel l2 which has been holding lever it retracted is moved out of the way to allow the spring on said lever to move the lever against the heart-shaped cam and force it back to zero position and thereby the spring recording hand 2i back to zero. It will be noted that the contrite ratchet teeth '11 are so cut that the faces of the teeth are in the direction of the motion of the train gear 5. In the form shown in the drawing the number of these contrite teeth represent the number of seconds in one revolution and each tooth is spaced to equal one second. In

the form shown in the drawing, the entire dial is marked off to represent one hundred seconds for one revolution of the pointer 2 i. The clutch wheel 3 preferably is shown for this particular form as five ratchet teeth 8 facing backwards, the number of these teeth being in accordance with the number of beats of the escapement in one second. In this particular instance the number of beats of escapement is five, since the form of chronograph shown is supposed to record to a second. These teeth 8 are spaced at equal distances apart so as to divide the contrite wheel teeth i into five equal parts. The wheel 5 has one hundred teeth thereon and the clutch wheel 3 has five teeth 8 thereon. These teeth 8 are so placed around the wheel 3 that each one is of the space between two contrite wheel teeth further advanced. For example, the distance between the end tooth 8 on the clutch wheel and. its adjacent tooth is equal to the distance covered by twenty and one-fifth contrite teeth on the train gear 5. Therefore, the distance between any one designated. tooth on the clutch wheel and. the third tooth on said wheel is equal to 40 and contrite teeth on the train gear and so on.

When these two gears, namely, the train gear and the clutch gear are, therefore, brought together no matter what the position of the train gear may be at the instant of engagement there will always be one of the clutch teeth which will fairly and fully engage in position between two contrite teeth so as to give a direct and positive engagement and what is called a complete hookup. Without this arrangement the forward movement which most always happens in chronographs heretofore made causes inaccuracies in the recording. In accordance with my invention the instant the pin 2!! is depressed or moved the pointer will start without any slippage since there is a positive and complete hook-up which starts the pointer ofi instantly and with complete accuracy and also insures that the pointer will always start at the zero point and will be found to register at a seconds mark accurately whenever the time is found to be in flat seconds. Otherwise the pointer will be found at rest on the proper of a second.

If the train gear 5 is cut at its upper surface with 100 contrite teeth then the clutch wheel 3 is cut with 99 teeth. After these 99 are cut all of them are milled off except five teeth leaving only the 20th, 40th, 60th and 80th teeth therein. It will be seen, therefore, that these teeth 8 in relation to the 100th teeth I on the train gear 5 will be of a tooth or /5 of a second. In the case of a train gear having only 60 teeth thereon the teeth are cut the same Way with only 59 on the clutch wheel and only five of these 59 left on. In this case the clutch will lift it at intervals of 12 contrite teeth, which would give a connection for three hundred possible hookups.

The number of teeth on the clutch wheel is regulated by and is the same as the number of beats of the escapement for one second. With an eighteen thousand escapement there would be five beats per second; with a twenty-one thousand six hundred train escapement there would be six beats per second and so on. In the case of a wheel revolving once every second and having one hundred teeth, when a clutch wheel having teeth spaced at intervals of ten on a ninety-nine hole plate the hook-up could occur over one thousandth of a second.

The invention, therefore, will be seen to provide a very simple form of construction between the train gear and the clutch plate which will promote an absolutely accurate and positive hook-up between said plates whenever starting pin 20 is actuated. No matter of the number of divisions each second of time is to be recorded the only requirement is that the train gear teeth and the clutch gear teeth be calculated in accordance with the above mentioned invention respectively dependent upon the seconds division desired. This differential relation between the number of the clutch teeth and the contrite teeth and their relative spacing always insures that no matter what hook-up takes place one tooth on the clutch wheel make a full and complete arrangement with the train gear so as to start the pointer off instantly and in full and accurate position. In combination with the brake element and the restoring lever 18 this mechanism provides full and complete accuracy, both as to their cooperative relation and as to their positions at any minute instant of time and both as to starting position and stopping position.

While the invention has been described in detail and with respect to a present preferred form thereof it is not to be limited to such details and forms since many changes and modifications may be made in the invention without departing from the spirit and scope of the invention in its broadest aspects. Hence it is desired to cover any and all forms and modifications of the invention which may come within the language or scope of any one or more of the appended claims.

What is claimed, is:

1. A chronograph mechanism which includes a driving plate having a hundred ratchet teeth thereon, a clutch plate having five ratchet teeth thereon, means for bringing said plate and gear in contact, the distance between the adjacent teeth and the clutch plate being equal to the distance between twenty teeth on the drive plate plus substantially one-fifth of the distance between adjacent teeth on the drive gear.

2. A method of constructing a detail of a chronograph which comprises forming a drive gear with a given number of teeth, milling a cooperative clutch plate with the same number of teeth minus one, removing all the teeth from the clutch plate except a predetermined number, the teeth on the clutch plate selected so that the distance between adjacent teeth on the clutch plate will be equal to the distance between a given number of teeth on the drive gear plus a fraction of the distance between adjacent teeth on the drive gear.

HENRY A. MORRISS. 

